Buick Disc Brake Conversion

I just purchased and put on a disc brake conversion for a 1968-1972 GM
A body car. My car is an 1971 Buick GS with the 350 Stage 1. I
purchase the kit off of ebay from waterloo tire company out of Iowa.
Of course it came with no instructions. I put on the parts myself and
could not get it to work. I took to local mechanic and he can't fiqure
out why it won't work. Here is a summary of what we did:

Installed new bearings, spindle and rotors. New SS braided hose. New
chrome power booster, master cylinder, proportioning valve and lines
from mastercylinder to proportioning valve. Had to get new lines to
rear becuase could not get fittings to match. Had new rubber brake
hose made from front to rear.

Here is what she is doing:
When car is turned off I have hard pedal. When cranked there is no
pedal. I have bench bleed master several times and power bleed it. I
can't get any pedal when it is cranked. No stopping except a if not
going fast rear brakes will lock up and gradually stop the car. I
plugged the master cylinder and it has hard pedal.

Any suggestions on what to do?

rpace.DeleteThis@rammbackhoe.com wrote:
> I just purchased and put on a disc brake conversion for a 1968-1972 GM
> A body car. My car is an 1971 Buick GS with the 350 Stage 1. I
> purchase the kit off of ebay from waterloo tire company out of Iowa.
> Of course it came with no instructions. I put on the parts myself and
> could not get it to work. I took to local mechanic and he can't fiqure
> out why it won't work. Here is a summary of what we did:
>
> Installed new bearings, spindle and rotors. New SS braided hose. New
> chrome power booster, master cylinder, proportioning valve and lines
> from mastercylinder to proportioning valve. Had to get new lines to
> rear becuase could not get fittings to match. Had new rubber brake
> hose made from front to rear.
>
> Here is what she is doing:
> When car is turned off I have hard pedal. When cranked there is no
> pedal. I have bench bleed master several times and power bleed it. I
> can't get any pedal when it is cranked. No stopping except a if not
> going fast rear brakes will lock up and gradually stop the car. I
> plugged the master cylinder and it has hard pedal.
>
> Any suggestions on what to do?
>
I can't comment on the hard pedal at rest vs the no pedal under
power....... it sounds like you touched all the bases, but did the
master you installed, have the fluid capacity to actuate the calipers,
vs the drum wheel cylinders. Disks require a lot more fluid,
especially if you installed them on all 4 wheels and the master has a
much larger bore. There is also the issue (on some cars) of the
actuator rod from the pedal into the master being adjusted correctly.